Rope chains made from precious metals have, for decades, been made largely by hand. The method of making such chains until this very day will now be described in detail with reference to FIGS. 7-10. The basic construction element, or component, of such rope chains is a ring formed of a solid or hollow wire, usually of precious metal, e.g. 14 karat gold. The ring 1 shown in FIG. 7 has an opening or gap 2 formed therein. This gap 2 has a narrow dimension 3 at its inner diameter and a wider dimension at its outer diameter.
The solid wire forming the ring (FIG. 8) usually has flattened sides 4 and rounded ends 5 which give the ring 1 a major diameter (d.sub.w) 6 and a minor diameter 7. The cross-section of the wire forming the ring 1 may also be of generally circular cross-section. The gap 2 of ring 1 is substantially larger than the minor diameter 7 and is slightly larger than the major diameter d.sub.w at its narrowest dimension 3.
A multiplicity of such rings 1 are intertwined to form, in outward apperance, a double helix, as shown in FIG. 9, which is the format for a standard rope chain. These tightly interfitting ring rope chains are hand-made as follows, based on the prior art teachings.
The ring 1 used for the chain should have an inner diameter (d.sub.i) slightly more than X times greater than the major wire diamter d.sub.w 6, and X equals 3 or an odd number greater than 3, e.g. 3.4. See U.S. Pat. No. 4,651,517 for a detailed discussion. Referring now to FIGS. 10a-10d, the first ring forming the rope chain will be termed herein the a ring. It is the first of a series of four rings forming a ring assembly. In the example of FIGS. 10a-10d X equals 3.
The relative orientation of the rings forming the rope chain is important. The a ring is initially oriented (manually) so that its gap, designated 20a, lies in a predetermined direction, e.g. facing generally upwardly, as in FIG. 10a. The second ring of this assembly, designated the b ring, is passed through the gap 20a of the a ring, with the gap 20b of the b ring facing downwardly at about 180.degree. removed from the a ring gap 20a, as shown in FIG. 10b. The a and b rings are juxtaposed and intertwined so that they lay against each other, with the periphery of the b ring lying against the periphery of the a ring, to the greatest extent possible, thereby creating a relatively large central opening 30 with the pair of intertwined abutting a and b rings. The plane of the a ring lies in parallel to the plane of the paper, and the plane of the b ring is slightly skewed from the a plane.
The gap 20c of the third ring c is then passed through the gap 20b of the b ring and over the minor diameter of the a ring and laid angularly against the a and b rings, the gap 20c of the c ring lying in the same orientation as the gap 20a of the a ring, and as shown in FIG. 10c, but with its plane more greatly skewed than the a and b rings. A central opening 30a still remains within the now three intertwined rings, a, b and c. The planes of each of the rings differ from each other by perhaps about 20.degree. because of their angular abutment. In the case where X equals 5, the planes of the rings would differ from each other by about 15.degree..
Turning now to FIG. 10d, the gap 20d of a fourth ring d is now passed over the a, b and c rings, through the central opening 30b, and thereby envelopes the a, b and c rings. The c ring is laid against the other rings (a-c) and its plane lies approximately 20.degree. from the plane of the c ring. The gap 20d of the d ring is disposed in the same orientation as the gap 20c of the d ring.
The just-described intertwining and orientation of a-d rings permits the continuation of the intertwining of additional assemblies of rings (of four rings each, where X=3, or six rings each when X=5 etc.) to create a "double helix" rope chain of a desired length. The adding on of an additional assembly of four rings is a repetition of the orientation previously described with reference to the a-d series, but the planes of this second assembly lie at approximately 90.degree. to the planes of the respective rings in the first assembly.
It is to be noted that the gaps of the first and third ring additions of a second ring assembly abut the previous first and third rings, and the second and fourth rings pass through the gaps of the previous second and fourth rings and that the relative orientations of the gaps of the rings altenate between adjacent rings about 180.degree.. Thus, as far as the operator is concerned, he or she is always alternating the gap orientation while intertwining each additional ring.
After building up the rings in the manner just described, to form the double helix rope chain (FIGS. 10a-10d, the rings are held in the desired juxtaposition temporarily by thin metal wire 25 wrapped about the rings (FIG. 9). Then solder S is intermittently applied, e.g. to every pair of adjacent rings ususally at two points of the external periphery thereof. The wire 25 is then removed. The intermittent soldering S results in a rope chain wherein every ring pair is slightly movable, with respect to its adjacent ring pairs, and results in a chain having the desired flexibility for forming a necklace or bracelet.
Rope chains having ring dimeter ratios with X being an odd number greater than 3 where disclosed in U.S. Pat. No. 4,651,517, which disclosure is incorporated herewith by reference.
As is apparent from the above description, the formation of such tight fitting rope chains is extremely complex and until now they have been manufactured almost entirely by hand, particularly by skilled and expert workmen. Because of the extremely small size of these rings, the linking of the open rings requires great dexterity and manual agility and continuous concentration on the part of the workmen. Since the rings must be overturned alternately through 180.degree. and simultaneously located so as to embrace a plurality of preceding rings, errors in the manual formation are far from infrequent. Thus the production of these chains by hand involves long periods of time and consequently is very labour-intensive which adds significantly to the selling price.
It is an object of the present invention to provide a fine jewelry rope chain produced manually with significant time saving.
It is a further object of the invention to provide a method for hand manufacturing a greater variety of fine jewelry rope chains with standard open rings than has been possible heretofore.